Role of extracellular polymeric substances in Cu(II) adsorption on Bacillus subtilis and Pseudomonas putida

摘要

The effect of extracellular polymeric substances (EPS) of Gram-positive Bacillus subtilis and Gram-negative Pseudomonas putida on Cu(II) adsorption was investigated using a combination of batch adsorption, potentiometric titrations, Fourier transform infrared spectroscopy. Both the potentiometric titrations and the Cu(II) adsorption experiments indicated that the presence of EPS in a biomass sample significantly enhance Cu(II) adsorption capacity. Surface complexation modeling showed that the pK_a values for the three functional groups (carboxyl, phosphate and hydroxyl) were very similar for untreated and EPS-free cells, indicating no qualitative difference in composition. However, site concentrations on the untreated cell surface were found to be significantly higher than those on the EPS-free cell surface. Infrared analysis provided supporting evidence and demonstrated that carboxyl and phosphate groups are responsible for Cu(II) adsorption on the native and EPS-free cells.